module mux4x64(
    input  [1:0] control,
    input  [63:0] a0,
    input  [63:0] a1,
    input  [63:0] a2,
    input  [63:0] a3,
    output [63:0] out
);
    assign out = control == 2'b00 ? a0 : (control == 2'b01 ? a1 : (control == 2'b10 ? a2 : a3));
endmodule
